4.6 - Watersheds

Question 1

What is a watershed?

Answer 1

All of the land that drains into a specific body of water (river, lake, bay, etc.)

Question 2

What is a runoff?

Answer 2

All water that runs to the main body of water; could be a stream, river, road, etc.

Question 3

What determines the direction of runoffs?

Answer 3

The slope of the land

Question 4

What three things play a role in how watersheds drain?

Answer 4

1. Vegetation
2. Slope
3. Soil Composition

Question 5

How does slope, vegetation, and soil help watersheds drain

Answer 5

1. More Vegetation = more infiltration and groundwater recharge
2. Greater slope = faster velocity of runoff and more soil erosion
3. Soil permeability = determines runoff vs infiltration rates

Question 6

What is infiltration?

Answer 6

When water is soaked through the soil and does not flow on top of the ground

Question 7

What human activities impact H2O quality?

Answer 7

1. Agriculture
2. Clearcutting
3. Urbanization
4. Dams
5. Mining

Question 8

What is an estuary?

Answer 8

the mouth of a large river where the tide meets the stream

Question 9

Why is the chesapeake bay a good example of an estuary?

Answer 9

The mix of fresh and saltwater with nutrients in the sediment makes estuary habitats like the salt marshes in the bay highly productive

Question 10

What ecosystem services do estuary’s and wetlands provide?

Answer 10

• water filtration: grassroots trap pollution
• Habitats for food sources: fish and crabs
• Storm protection: absorbing and buffering floods
  All of this makes them an ideal spot for hotels and tourism too

Question 11

How does Nutrient Pollution (N/P) lead to eutrophication?

Answer 11

1. Algae bloom due to an increase of N/P
2. Causes decreased sunlight on the body of water
3. plants below the surface die from no sunlight
4. Bacteria uses up the O2 to decompose the dead plants
5. Hypoxia (low O2) occurs, which creates dead zones

Question 12

What is eutrophication?

Answer 12

Excessive richness in nutrients from runoff from surrounding land which causes a dense growth of plant life and the death of animals from lack of O2

Question 13

What are major N/P sources?

Answer 13

1. Discharge from sewage plants (M/P levels from human waste)
2. Animal waste from CAFOs (concentrated animal feeding operation; livestock grown to be eaten)
3. Synthetic fertilizer from agriculture fields and lawns

Question 14

Aside from N/P what are important pollutants for watersheds?

Answer 14

1. Endocrine disruptors: from sewage treatment
2. Sediment pollution: deforestation, urbanization, tilling agriculture fields, etc.

Question 15

What are the two direct effects clearcutting?

Answer 15

1. Soil erosion
2. Increased soil and stream temperatures

Question 16

What effect does clearcutting have on soil erosion?

Answer 16

• caused by loss of stabilized root structure
• removes soil organic matter and nutrients from the forest
• deposits sediment into local streams
  - warms the water and makes it more cloudy

Question 17

What effect does clearcutting have on soil and stream temperature?

Answer 17

• loss of tree shade increases soil temperature
• loss of tree shade along rivers and streams warms them
  - erosion of sediments into rivers also warms them

Question 18

What is clearcutting?

Answer 18

the process of cutting and clearing every tree from an area